The goal of this research is new information on the pre- and post-natal development of the otolith organs and on involvement of the vestibular labyrinth in ear pathology. A combination of light and electron microscopic methods will be used to study the otoconial membranes and neuroepithelia of the human saccule and utricle. In addition, microanalytic procedures will be used to gather data on the mode and time course of calcium deposition in the developing otoconia. Vestibular system pathology will be studied as appropriate cases become available. This phase of the project will concentrate on congenital defects and on the relationship of otitis media to inner-ear pathology. Work with human material will be supported and extended by developmental studies in the mouse. In this portion of the investigation we expect to clarify certain aspects of functional development of the otolith apparatus in the experimental animal.